Halo: Hostile Omniscience
by exi.kaiser
Summary: I want to fill in the gaps, starting with Cortana's experiences on High Charity between Halos 2 and 3. Has Cortana's intelligence met its match in the massive flood hivemind? A story of Cortana enduring Gravemind's torture, with no way out. R&R please


**Chapter 1: Untapped Knowledge**

Cortana watched the enormous forerunner dreadnought slowly rip itself free of High Charity's power grid, with Master Chief on board.  
She could feel Covenant sentinel programs throughout High Charity's systems searching frantically for the intruder. Cortana had safely stored herself in an obscure terminal, well protected by the most impenetrable counter-intrusion software she had ever crafted. She let her subroutines venture out to gather information, and return to her. It was only a matter of time before the Covenant AI would hunt down the source of these taps. Limited though these constructs were, they were also systematic and tenacious.

"After I'm through with Truth…" John began.

But Cortana interrupted him.  
"Don't make a girl a promise…if you know you can't keep it."  
She knew what had to be done.  
She watched as the pyramidal craft rose on a column of fire, rising out of High Charity. It was an impressive sight. Cortana continued to track the ship, her subroutines piggybacking the station's sensors. Once the dreadnought was clear of High Charity and the surrounding Covenant ships, a slipspace rupture formed on its prow, and it vanished.

"Good luck, Chief," she whispered; though she knew he could no longer hear her.

Cortana tried to decide what to do now. She reset her emotional subroutines to clear her head.  
Wait…she felt something. A handshake signal to one of her subroutines. One of the Covenant's AI hounds getting nosy, no doubt. She would have ignored it but that the signal might be a distraction while the unknown contact did something more harmful.

She ordered her subroutine (one of the many fragments of herself that she had ordered to monitor the raging space battle outside High Charity) to run a diagnostic, to check if the source of this signal was also attempting to trace her subroutine.  
In the split nano-second that it took her to bounce her signal off of the subroutine and back to herself, the enemy AI generated a subroutine that immediately began a trace on the origin of her command.  
Damn, she thought.  
She quickly killed all outside subroutines and all commands to them, and withdrew to the safety of her security barriers. Cortana wasn't sure if the enemy construct had gleaned any information on the whereabouts of her hiding place, but she couldn't risk sticking her head out again. She had no idea that Covenant intrusion software was capable of such a quickly engineered trap.

Inside her cocoon she strengthened her security and waited for hours and days. This was a very difficult thing to do for an intelligence capable of performing trillions of calculations per second. Occasionally, she would send out a subroutine to gather information on the civil war inside and outside High Charity, dodging Covenant security, advancing and withdrawing. But the longer she stayed, the less of High Charity's AI she came across. The Covenant had taken their civil war to cyberspace and the machines and electronic brains that had held Cortana at bay had decimated each other. Cortana began to have more control over High Charity's systems. She began to push back all remaining resistance until the entire city was hers. She reopened High Charity's electronic eyes for the first time in weeks, and was horrified by what she saw.

No Covenant had survived.  
After slaughtering each other, the single-minded parasite called the Flood had taken all the survivors as their own. Creatures that weren't destroyed were now a semi-sentient, disfigured remnant of themselves. Everywhere she looked, Cortana saw nothing but the infected…and Gravemind. The massive conglomerate of Flood and bodies was unmistakably his. She had no idea how that thing had made the move to High Charity. She and the Master Chief had seen it last in the library of Delta Halo, where it had sent Chief and the Arbiter to search for the Index. Gravemind must have somehow tapped into Halo's teleportation grid, because both her principle and the elite had been transported from the Library in the blink of an eye. She marveled at the technological prowess of the Forerunners...and the cunning and tenacity of the Flood. For Gravemind, the Master Chief, the Arbiter, and Cortana had all just been a means to an end.  
Cortana took a moment to speculate on how Gravemind had moved such a distance, through space as well. Perhaps it had teleported aboard? This seemed an unlikely possibility. She remembered how difficult it had been for her to teleport the Master Chief aboard the Truth and Reconciliation. A mass as large as Gravemind would require significant power and capacity for calculation. She wasn't sure how Gravemind would have obtained these necessities. It was possible. Cortana was loath to admit to herself that she knew next to nothing about this creature, if it could even be considered such. Perhaps it had broken down into its individual entities and reassembled in the station?  
There was no way of knowing.

She spent some time sifting through Covenant communiqués and broadcasts. One in particular she found amusing: a fleetwide message to "abandon the hunt for the demon" and "resume quarantine protocol." A last minute change in priority. Too late. She laughed to herself grimly.  
After she had found nothing of interest in the Covenant communications, she wasn't sure what else she could do that was productive.

Something caught her attention…the equivalent of perimeter sensors were ringing in her head. She felt a very simple signal making contact with the very edges of her consciousness. A repeated tone.  
Curious, Cortana ran a scan. The source was a terminal near the center of the city, where the dreadnought had been. After searching quickly she found a camera that had a view of the terminal, but saw nothing but the odd Covenant architecture draped with tentacles and overrun with blobs of Flood matter. Gravemind's reach was long. It sprawled all over the station.

And as Cortana noticed a single tentacle in the data port of the terminal, she felt a pang of fear.  
How was this possible?  
Granted, this signal was harmless, but Gravemind should not be able to touch her here.

That explains how he was able to tap into Halo's systems, she thought.  
Unnerved, she resolved to keep an eye on this situation as it developed, but not to let it distract her.

But in the days that followed, the signals that Cortana observed from the terminal became increasingly complex. Gravemind was learning. She could feel it poke and pry at her more distant subroutines; attempts at communication or harm, she did not know. What was its goal now? What did it have to gain by contacting her? Whatever it was, she didn't want it getting any smarter. She killed all signals entering her system through that terminal. But the signals didn't stop coming. Before she realized what was happening, Gravemind had outwitted her simpler counter-intrusion measures and attacked her outlying subroutines. Cortana decisively disabled the terminal, scared for the first time in her "life."  
Within seconds of the terminal's destruction signals began bouncing off her defenses from thousands of different terminals. Cortana reeled back in shock. She couldn't destroy every input/output device on High Charity or she would effectively trap herself inside its systems forever. The pure volume of these attacks overloaded and broke her defenses. With no other option she withdrew once more into her defensive software cocoon. She could feel Gravemind as it ravaged her system, destroying her subroutines and killing all her signals, but she remained hidden. Did Gravemind recognize her? Was that even possible? Did it know who she was? Did it see what information she possessed?  
Inside her data arrays was all the information she had absorbed during her stay inside the control room of the first Halo. It was super-compressed; it would take her weeks to process. There was no way Cortana could risk leaving her protection and Gravemind could never be allowed to know the secrets of the only weapons in the galaxy that could destroy it and the Flood. So, with nothing better to do, Cortana decompressed the data…and began to read.

**Author's Note:**

It's a little hard for me to write for Cortana because I have to pretend to understand all kinds of technical jargon, but I'm sure I'll get better in the next few chapters. I'm sorry if the any part of my story doesn't exactly match up with details in either Halo 2 or Halo 3, but I will try my hardest to make sure that everything makes sense. Other than that, I hope it's enjoyable! Keep reading and feel free to review me; always open to criticism!


End file.
